1. Field
The present invention relates generally to the bonding of components in an electronic system.
2. Relevant Art
Microprocessors and many other complex electrical components may consist of a package that houses an integrated circuit (IC). The package, which acts as an electrical bridge between the IC and a printed circuit board, includes a substrate and an internal metallurgy system that routes power, ground, and signals between the printed circuit board and an IC attached to the substrate.
A package is typically connected to a printed circuit board using either a set of input/output pins (e.g., a “pin grid array”) or solder balls (e.g., a “ball grid array”). In a pin grid array package, arrays of input/output pins are connected to the bottom surface of the package. During assembly of a printed circuit board, the pin grid array is mated to a complimentary socket on the printed circuit board. One advantage to using pin grid array packages is that the package can later be removed from the printed circuit board and replaced.
Two technologies for manufacturing pin grid array packages are commonly used in the semiconductor manufacturing industry. These technologies are surface mount technology and wire bond technology. Surface mount technology involves attaching pins to conductive pads on the bottom surface of a ceramic substrate, thus forming electrical connections with the internal package routing system.
Because organic packages cannot be heated to extremely high temperatures without becoming damaged, and because it is impractical to surface mount pins using commonly used tin-lead (Sn—Pb) solder, wire bond technology is generally used to create organic packages with pin grid arrays.
Wire bond packages are generally larger than the IC that a package houses, since the package must accommodate the peripheral, inserted pin grid array. In order to reduce the size of organic packages, “flip-chip” ball grid array packages may be used. A “flip-chip” is a chip in which power, ground, and signal leads are brought to pads anywhere on the top surface of the chip. Sn—Pb solder bumps are then printed onto the pads, and the chip is turned upside down, and aligned with pads on the top surface of the package.
On the bottom of the package, a ball grid array is provided in order to attach the package to the printed circuit board. The ball grid array generally consists of solder balls that are attached to pads on the bottom of the package. These pads are then aligned with matching pads on the printed circuit board, and the board is heated, causing the solder to melt and form contacts between the package pads and the board pads. Flip-chip ball grid array packages can be substantially smaller than wire bond packages.
Connections are made in electronic systems by flip chip ball grid arrays (BGA), and other BGA types, for example, Flip Chip BGA, Wire Bond Plastic BGA, Ceramic BGA, micro BGA, very fine BGA, T-BGA, Chip Scale Package, etc.
There is a need in the art for a strong, stable bond between components in an electronic system.